Enzymes (WIP)

Eduqas Core concepts alevel bio

What are enzymes

globular proteins and biological catalysts. They are not used up.

Enzyme active sites

Enzymes are specific as they have an active site which is complementary to the shape of the substrate. Depends on the tertiary structure of enzyme.

Metabolism

all the enzyme/ chemical reaction in a cell

Anabolism

the reactions that build up new, more complex molecules from seperate substrates

Catabolism

the reactions that break down more complex molecules into seperate products 

Metabolic Pathways

a series of reactions where the product of one enzyme is the substrate of another one

Extracellular enzymes

They work outside of the cell eg. digestive enzymes are made in pancreatic cells and then transported out of the cell to digest food in the gut

Intracellular enzymes

work inside the cell. eg. enzymes for aerobic respiration are found in mitochondria

How do enzymes work?

• When a substrate and an active site collide the substare binds to the active site through interactions in the R group making an enzyme-substrate complex

• Bonds in the substrate distort, straining the bonds that would break and increase the chance of them breaking

• This brings new atoms in the substrate closer and new bonds can form

Activation energy required for the reaction decreases once they bond

Lock and key theory

The active site is a fixed shape. The substrate collides with the active site in the correct oritientation.

Induced fit theory and an example.

As the substrate enters the active site forces of attraction are formed which causes the active site to change shape to fit the substrate.

Activation energy graph